problem with stream buffer

Hello experts,

i have one query which i am not able to solve please suggest me my problem is i have to open a filedescriptor and have to store the contents in streambuffer,

i,e

Code:

int main () {

 char ch;
 streambuf * pbuf;size_t size;
  ifstream istr(const char *)fd);
  pbuf = istr.rdbuf();

  while (pbuf->sgetc()!=EOF)
  {
     ch = pbuf->sbumpc();
     cout << ch;
  }

  istr.close();

  return 0;
}

but here the line

Code:

ifstream istr(const char *)fd);

is not properly interpreting thats why there is no out put

if i simply give

Code:

ifstream istr(fd);

it gives me error as this method does not exist,
please helop me what to do but i want the result in <b>streambuffer</b> because this is the input for some other module in my project pleasesuggest what are the different way i can get so the i get the contents in <b>streambuffer.</b>

thanks in advance.